This invention generally relates to perfusion type intravascular catheters and particularly to perfusion type balloon dilatation catheters used in percutaneous transluminal coronary angioplasty (PTCA).
In typical PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into the cardiovascular system of a patient and advanced therein until the preshaped distal tip of the guiding catheter is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end to turn the distal tip of the guiding catheter so that it can be seated in the desired coronary ostium. With over-the-wire balloon dilatation catheter systems, a guidewire and a balloon dilatation catheter are introduced into and advanced through the guiding catheter to the distal tip thereof, with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is first advanced out the distal tip of the guiding catheter until the distal end of the guidewire crosses the lesion to be dilated. The dilatation catheter is then advanced out of the distal tip of the guiding catheter, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-12 atmospheres) to dilate the stenosed region of the diseased artery. One or more inflations may be necessary to effectively dilate the stenosis. Additional stenoses may be dilatated with the same catheter. When the dilatations have been completed, the balloon is deflated so that the dilatation catheter can be removed from the dilated stenosis and an adequated blood flow will resume through the dilated artery.
The assignee of the present application, Advanced Cardiovascular Systems, Inc., has introduced improved dilatation catheters into the market place under the trademarks STACK PERFUSION.RTM. Coronary Dilatation Catheter and the RX Perfusion.TM. Dilatation catheter which have a plurality of perfusion ports in the wall of the catheter shaft proximal to the balloon and has one or more perfusion ports in the catheter shaft distal to the balloon. The perfusion ports are in fluid communication with a guidewire receiving inner lumen which extends to a guidewire port in the distal end of the catheter body. When the balloon on the distal extremity of the dilatation catheter is inflated to dilate a stenosis, oxygenated blood in the artery or the aorta or both, depending upon the location of the dilatation catheter within the coronary anatomy, is forced to pass through the proximal perfusion ports, through the inner lumen of the catheter body and out the distal perfusion ports. This provides oxygenated blood downstream from the inflated balloon to thereby prevent or minimize ischemic conditions in tissue distal to the catheter when the balloon is inflated. As is appreciated by those skilled in the art, tissue distal to a stenosis is frequently already in jeopardy due to ischemic conditions which may result from the stenotic region within the artery. Therefore, care must be exercised in sizing the perfusion ports and the inner lumen to ensure that there is adequate flow of oxygenated blood to tissue distal to the catheter during the dilatation to eliminate or minimize resulting ischemic conditions. These perfusion catheters have been widely praised and have met with much commercial success.
The ACS RX.RTM. Perfusion Coronary Dilatation Catheter is described and claimed in copending application Ser. No. 07/888,253, filed on May 22, 1992, which is incorporated herein in its entirety by reference. The catheter described in the aforesaid copending application has a short guidewire receiving sleeve or inner lumen extending through a distal portion of the catheter a short distance from a first guidewire port in the distal end of the catheter to a second guidewire port in the catheter spaced proximally a short distance from the inflatable member of the catheter. The second guidewire port is spaced a substantial distance from the proximal end of the catheter and usually about 10 to about 50 cm from the first guidewire port in the distal end of the catheter. A slit in communication with the guidewire receiving inner lumen may be provided in the wall of the catheter body which extends distally from the second guidewire port to a location proximal to the perfusion ports which are proximal to the inflatable balloon. The structure of this catheter allows for the rapid exchange of the catheter without the need for an exchange wire or adding a guidewire extension to the proximal end of the guidewire and the additional feature of providing perfusion of oxygenated blood distal to the catheter when the balloon is inflated within the patient's coronary artery.
One of the problems encountered with the use of perfusion type catheters has been that it is not uncommon for the guidewire to pass through a perfusion port when it is advanced through the inner lumen of the catheter. Efforts have been made to eliminate this problem by providing a barrier within the perfusion port(s) but this has not met with much success. For example, perfusion catheters have been designed wherein a single perfusion port is provided proximal to the inflatable balloon which is has an interior barrier to prevent the excursion of a guidewire through the single perfusion port. However, in this design, if for some reason the single port is pressed against the arterial wall or otherwise blocked or occluded, the flow of oxygenated blood distal to the catheter can be reduced considerably causing the patient to be put in jeopardy due to the ischemic conditions which may be created.
What has been needed and heretofore unavailable is a perfusion type intravascular catheter which will prevent guidewire excursions through the perfusion ports and will also ensure an adequate flow of oxygenated blood distal to the catheter to prevent dangerous ischemic conditions from existing distal to the catheter for any significant periods of time. The present invention satisfies these and other needs.